The objective of this project is development of new mass spectral techniques in order to provide innovative and/or more rapid solutions to problems involving (1) chemical structure determination, (2) complex mixture analysis and (3) measurement of trace components in biological systems. Electrospray ionization mass spectrometry (ESI/MS), tandem mass spectrometry (MS/MS), combined liquid chromatography-mass spectrometry (LC/MS), combined capillary electrophoresis-mass spectrometry (CE/MS) and matrix-assisted laser desorption ionization (MALDI) mass spectrometry are the techniques of current interest. Narrow-bore, reversed-phase liquid chromatography has been combined with tandem mass spectrometry to develop a general purpose system for characterizing and measuring nucleoside-based drugs in biological samples. On-line sample concentration techniques are being investigated as a prelude to interfacing CE to nano-electrospray ionization mass spectrometry for the analysis of intracellular nucleotide metabolites. Preparative-scale CE is also being investigated as an off-line method for combining CE with high resolution MALDI/MS and post-source decay fragmentation analysis. Fast atom bombardment mass spectrometry (FAB/MS) is employed to support the LMC synthetic effort through structural characterization of new compounds and synthetic intermediates. Studies to confirm the structural identity of compounds identified as HIV-1 integrase inhibitors through 3-dimensional database searching continue. A project to evaluate the quality of compounds in the NCI chemical database using MS and NMR analysis for structural characterization and determination of purity is nearing completion. Statistical and clustering methods have been used to select compounds representative of the structural diversity of this publically accessible, small molecule database of over 250,000 structures for analysis. Since 31% of the compounds examined have been rated as unacceptable (no spectral evidence for the presence of the desired compound or contaminants exceed 50% of the sample), care must be exercised in using compounds from this database. AIDS Title: Application of New Mass Spectral Methods for the Analysis of Anti-AIDS Agents